Alternative Text (Alt Text)
When you add an image to a website, document, or social media post, a sighted person can instantly understand what it shows. But for someone using a screen reader, assistive technology that reads digital content aloud, an image without a text description is invisible. That’s where alternative text, or alt text, comes in.
What is Alt Text?
Alt text (alternative text) is a brief text description of an image that:
- Is read aloud by screen readers
- Appears if the image fails to load
- Helps search engines understand your content
Alt text ensures that people with visual impairments receive the same meaning from your content that a sighted person would.
How to Write Effective Alt-Text
Describe the MEANING, Not the APPEARANCE
Ask yourself: "If someone can't see this image, what information do they need to know?"
Alt text should communicate the purpose of the image in its context.
Good alt text is:
- Concise – 1–2 sentences (generally under 125 characters when possible)
- Descriptive – Focuses on what matters
- Contextual – Meaning depends on where it appears
- Written in plain language – Use your own words
Avoid:
- Leaving the alt field blank (unless decorative)
- File names like “IMG_5847.jpg”
- Generic phrases like “image” or “photo”
- Writing a paragraph
- Starting with “Image of…” or “Picture of…”
Screen readers already announce it as an image — just describe it directly.